A digital image based on the RGB (Red Green Blue) color model has pixels composed of three primary color components: red, green, and blue. The additive combination of the three component color intensities determines the final pixel color. It is useful to think of the digital image as having three separate color channels, each channel describing pixel intensities for only one color component: red, green, or blue. RGB channels roughly follow the color receptors in the human eye and are used in computer displays and image scanners.
If an RGB image is 24-bit, each of the three channels is allotted 8 bits to represent the channel's color component intensity value for each pixel. One might think of such an RGB image as being composed of three grayscale images, each the same dimensional size as the RGB image and representing a channel associated with a color component, where each grayscale image can store discrete pixels with luminance values between 0 and 255 (e.g. 8-bits). Also one might describe a pixel in the RGB image as an ordered tuple whose first element represents a pixel value in the grayscale image for red, whose second element represents a pixel value in the grayscale image for green, and whose third element represents a pixel value in the grayscale image for blue. An example of such a tuple is (32, 64, 128), where the luminance for blue is twice the luminance for green and the luminance for green is twice the luminance for red. An example of a maximum pixel value expressed using such a tuple is (255, 255, 255), typically associated with the color white. An RGB image pixel is described as gray if each element in the tuple has the same value (e.g. all color components have equal influence). Otherwise, the RGB image pixel is described as having color.
When trying to create a display from a system of multiple projectors, a desirable attribute is seamlessness. That is to say, the display from one projector in the system should not be easily discernable by the human eye when combined with the displays from the other projectors in the system. Disparities with respect to the luminance resulting from individual projectors in the system detract from such seamlessness, though such disparities are perhaps inevitable due to factors like device settings, lamp age, panel and filter alignment, and even the reflectivity of the display surface.